Split crimper for heat sealing packaging material

ABSTRACT

A split crimper for use in a crimping assembly for engaging and heat sealing overlapping layers of a packaging material includes a first crimper portion having a crimping surface and a second crimper portion that is secured to the first crimper portion to form a crimper. Portions of the first and second crimper portions cooperate to define an interior cavity, and a heating element is disposed completely within the interior cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/636,468, filed Dec. 16, 2004, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

This invention relates in general to form, fill, and seal packagingmachinery of the type in which a continuous sheet of a packagingmaterial is sequentially folded about a series of articles to bepackaged, sealed about the articles, and cut into individually sealedpackages. More specifically, this invention pertains to an improvedcrimper for heat sealing overlapping end portions of the sheet ofpackaging material after it is folded about an article.

The formation of a plurality of individually sealed packages of articlesusing a single continuous sheet of a packaging material is well known inthe art. Briefly, the sheet of packaging material is initially passedthrough a folding mechanism, which continuously folds the film over onitself to form an enclosure for a series of spaced apart articles. Theoverlapping portions of the film are then sealed along a continuouslongitudinal seal. Next, the folded sheet of packaging material is fedto a sealing and cutting assembly that seals the leading and trailingedges of the package to be formed about the enclosed article and cutsthe tube into a plurality of individually sealed packages. In someinstances, it is desirable to apply heat during the process of sealingthe overlapping portions of packaging material. Packages produced bythis form, fill, and seal process are commonly used for snack bars,candy, cereals, and the like, as well as for other non-food articles.

The sealing of the overlapping end portions of the sheet of packagingmaterial is frequently accomplished by a mechanical crimping assembly. Aconventional mechanical crimping assembly includes a pair of opposedcrimpers that are disposed on opposite sides of the overlapping portionsof the sheet of packaging material. The crimpers can include one or moreheating elements to provide heat during the sealing process. Thecrimpers have undulating or serrated crimping surfaces defined byadjacent peaks and valleys. When the opposed crimpers are moved intoengagement with the overlapping portions of the sheet of packagingmaterial, the peaks of the first crimping surface are aligned with thevalleys of the second crimping surface, and vice versa. Such engagementcompresses the overlapping portions of the sheet of packaging materialto form an intermeshing seal pattern.

During the crimping and sealing process, it is important that thecrimpers exert a sufficient amount of force to compress the overlappingportions of the sheet of packaging material. If an insufficient amountof force is exerted by the crimpers, then the overlapping portions ofthe sheet of packaging material will not be compressed sufficiently toform a complete seal. At the same time, however, it is equally importantthat the amount of force exerted by the crimpers not exceed the strengthof the sheet of packaging material. If an excessive amount of force isexerted by the crimpers, the sheet of packaging material will tear orbreak. Thus, it is desirable that the amount of force which can beexerted by the crimpers against the overlapping portions of the sheet ofpackaging material remain within a predetermined range to insure acomplete and secure seal.

The distance between the opposed crimpers on the crimping assemblydetermines the amount of force exerted by the crimpers against theoverlapping portions of the sheet of packaging material. In order toinsure that the amount of force exerted by the crimpers remains withinthe predetermined desired range, the set-up of the crimpers on thecrimping assembly must be performed very carefully. As a result, theset-up is a very time consuming operation.

It has been found that the heating element and the wires attachedthereto are relatively fragile and are prone to failure. In the past,replacement of these components required removal of the crimper from thecrimping assembly. This was relatively expensive process because of theset-up time required to replace the crimper on the crimping assembly.Sometimes, replacement of these components required replacement of theentire crimper, which incurred both the set-up time expense and the costof the new crimper.

Recently, a crimper has been developed which does not require completeremoval from the crimping assembly to replace the heating element. Asshown in FIGS. 1 and 2, this crimper 10 includes a base 12 that ismounted on the crimping assembly and a top 14 that is removably attachedto the base 12 with threaded fasteners 15. Respective grooves 16 and 18are provided in the top 14 and the base 12 that define a bore 20 thatextends longitudinally therethrough. A conventional heating element 22(shown in FIG. 2) is disposed within the bore 20. The end of the heatingelement 22 is exposed at the opening of the bore 20, inasmuch as it isnot protectively covered by any portion of the top 14 of the crimper 10.Electrical wires 24 attached to the end of the heating element 22 extendoutside the bore 20. When it is necessary to replace the heating element22, the top 14 is removed from the base 12, the heating element 22 isreplaced, and then the top 14 is re-attached to the base 12. During thisprocess, the base 12 remains mounted on the crimping assembly so that itis not necessary to perform a relatively time-consuming set-up operationafter replacing the heating element 22. Unfortunately, the singleheating element 22 in this crimper design does not always providesufficient heat during a sealing operation. Another drawback is that therelatively fragile junction between the electrical wires 24 and theheating element 22 is left exposed in this design, as discussed above.Thus, it would be desirable to provide an improved structure for acrimper that addresses these drawbacks, while still avoiding therequirement for a relatively time-consuming set-up operation.

SUMMARY OF THE INVENTION

This invention relates to an improved structure for a split crimper thatis adapted for use in a crimping assembly for engaging and heat sealingoverlapping layers of a packaging material. The crimper includes a firstcrimper portion having a crimping surface and a second crimper portionthat is secured to the first crimper portion to form a crimper. Portionsof the first and second crimper portions cooperate to define an interiorcavity, and a heating element is disposed completely within the interiorcavity.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a prior art heated crimper for usein a crimping assembly.

FIG. 2 is an exploded end elevational view of the crimper illustrated inFIG. 1.

FIG. 3 is a schematic perspective view of a form, fill, and sealapparatus for packaging articles including a rotary crimping assembly inaccordance with this invention.

FIG. 4 is an enlarged sectional elevational view of a portion of theform, fill, and seal apparatus taken along line 4-4 of FIG. 3, showingthe sheet of film partially wrapped about an article.

FIG. 5 is an enlarged sectional elevational view of a portion of theform, fill, and seal apparatus taken along line 5-5 of FIG. 3, showingthe sheet of film fully wrapped about the article, but prior to beingsealed and cut into individually sealed packages.

FIG. 6 is an exploded perspective view of a split crimper according tothe invention, including two heating elements, that is adapted for useas part of the rotary crimping assembly of FIG. 3.

FIG. 7 is a perspective view of the split crimper of FIG. 6 showing theheating elements positioned inside the base of the crimper and showingthe underside of the top of the crimper.

FIG. 8 is a perspective view of the split crimper of FIG. 7 showing thetop of the crimper positioned on the base of the crimper and the heatingelements inside the crimper.

FIG. 9 is a side sectional view of the split crimper of FIG. 8 showingthe top of the crimper attached to the base of the crimper and one ofthe heating elements inside the crimper.

FIG. 10 is an end sectional view of the split crimper of FIGS. 8 and 9showing the top of the crimper attached to the base of the crimper andboth of the heating elements inside the crimper.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, there is schematically illustrated in FIG. 3a form, fill, and seal apparatus, indicated generally at 26, inaccordance with this invention. The apparatus 26 is generallyconventional in the art, and only those portions that are necessary fora complete understanding of this invention will be explained in detail.The apparatus 26 includes means for supporting a roll 28 of aconventional packaging material, such as polypropylene films, saranfilms, or laminations of a plurality of films. A sheet 30 of thepackaging material is payed out from the roll 28 and fed around variousrollers 32 to a folding shoe 34. The folding shoe 34 is conventional inthe art and is provided to continuously fold the longitudinal edges ofthe sheet 30 of packaging material about the sides of a plurality ofarticles 36 that are moved longitudinally along a conveyor 38. Thefolded sheet 30 of packaging material is then moved along a supportsurface 40.

As the folded longitudinal edges of the sheet 30 are moved along thesupport surface 40, they are engaged by a pair of folding rollers 42disposed beneath the support surface 40. As a result, the longitudinaledges of the sheet 30 of packaging material are further foldeddownwardly in an overlapping manner, as shown in FIG. 4. Then, a pair ofgrooved heat seal rollers 44 disposed beneath the support surface 40engage the overlapping edges of the sheet 30 of packaging material so asto create a continuous longitudinal fin seal 30 a. The fin seal 30 a isnext engaged by a pair of pull rollers 46, also disposed beneath thesupport surface 40, which advance the folded sheet 30 of packagingmaterial (and the articles 36 enclosed therein) through the apparatus26. A deflector 40 a is provided in the support surface 40 to fold thefin seal 30 a upwardly into flush engagement with the folded sheet 30 ofpackaging material, as shown in FIG. 5.

A rotary crimping assembly, indicated generally at 48, is provided inthe apparatus 26 for laterally crimping and cutting the folded sheet 30of packaging material so as to form a plurality of individually sealedpackages, such as shown at 36 a in FIG. 3. The crimping assembly 48includes an upper crimper bar 50 that is disposed above the supportsurface 40 for rotation about an axis extending generally perpendicularto the longitudinal movement of the sheet 30 of packaging material. Apair of upper crimpers, indicated generally at 52, are attached toopposite sides of the upper crimper bar 50 for rotation therewith.Similarly, the crimping assembly 48 includes a lower crimper bar 54 thatis disposed below the support surface 40 for rotation about an axisextending generally perpendicular to the longitudinal movement of thesheet 30 of packaging material. A pair of lower crimpers, indicatedgenerally at 56, are attached to opposite sides of the lower crimper bar54 for rotation therewith.

FIGS. 6 through 10 illustrate a preferred embodiment of a split crimper58 according to the invention. The split crimper 58 can be used as oneor both of the upper crimpers 52 and/or as one or both of the lowercrimpers 56 shown in the crimping assembly 48 shown in FIG. 3.Preferably, all of the upper and lower crimpers 50 and 54 are splitcrimpers 58 in accordance with this invention.

The split crimper 58 comprises two or more crimper portions that areremovably attached to one another to form the crimper 58. In theillustrated embodiment, the split crimper 58 comprises a first crimperportion, which is a base 60, and a second crimper portion, which is atop 62. In an alternate embodiment (not shown), the split crimper couldcomprise left and right crimper halves. FIGS. 6 and 7 show the top 62removed from the base 60, FIG. 8 shows the top 62 positioned on the base60, and FIGS. 9 and 10 show the top 62 attached to the base 60. Asillustrated in FIG. 8, the split crimper 58 is generally rectangular inshape and is somewhat elongated.

The base 60 of the split crimper 58 is adapted for attaching to theupper crimper bar 50. The base 60 extends along a portion of the uppercrimper bar 50 and is secured thereto by any conventional means (notshown). The base 60 includes a lower surface 64 which abuts a mountingsurface (not shown) provided on the upper crimper bar 50 when attachedthereto. In the preferred embodiment shown, the lower surface 64includes a plurality of spaced apart pads 66 that protrude from thelower surface 64. The pads 66 abut the mounting surface of the crimperbar 50 when the split crimper 58 is attached thereto, leaving theremaining areas of the lower surface 64 spaced apart from the mountingsurface. This optional arrangement minimizes heat transfer between thesplit crimper 58 and the crimper bar 50 during the crimping operation.Alternatively, the lower surface 64 could be formed without the pads 66or with different structures (not shown) to minimize heat transfer. Ifthe mounting surface on the crimper bar 50 is rounded, the pads 66 canbe formed to have a radius (not shown) which matches the contour of themounting surface. In a preferred embodiment, the base 60 is attached tothe upper crimper bar 50 by the use of threaded fasteners (not shown)extending from the crimper bar 50 into threaded holes (not shown) inbottom of the pads 66.

The top 62 of the split crimper 52 has an upper surface 68. The uppersurface 68 includes a longitudinally extending, outwardly facingcrimping surface 70. The crimping surface 70 is formed having any typeof cross sectional shape suitable for performing the sealing operation,preferably an undulating cross sectional shape. The illustrated uppersurface 68 also has a longitudinally extending slot 72 that extendsalong the center of the upper surface 68. The slot 72 divides thecrimping surface 70 into a leading portion 74 and a trailing portion 76.A conventional cutting blade (not shown) or a conventional anvil (notshown) is disposed within the slot 72. The slot 72 has an enlarged end78 that receives an enlarged end portion of the blade or anvil. Anopening 80 that extends to the enlarged end 78 of the slot 72 allows theinsertion of a threaded fastener (not shown) into a threaded hole in theenlarged end portion of the blade or anvil to secure it in place. A pryslot 82 is provided at the other end of the slot 72 to assist in removalof the blade or anvil from the slot 72. The purpose of the cutting bladeand the anvil will be described below.

The base 60 and the top 62 of the split crimper 58 define at least oneinterior cavity 84 (see FIG. 10) that is adapted for totally enclosing aheating element 86. In the preferred embodiment shown, the base 60 andthe top 62 define first and second interior cavities 84 and 88 (see FIG.10) that are adapted for totally enclosing first and second heatingelements 86 and 90, respectively. As shown in FIGS. 6 and 7, the firstinterior cavity 84 is defined by the combination of a first groove 84 ain an inner surface 92 of the base 60 and a first groove 84 b in aninner surface 94 of the top 62. The second interior cavity 88 is definedby the combination of a second groove 88 a in the inner surface 92 ofthe base 60 and a second groove 88 b in the inner surface 94 of the top62. The first grooves 84 a and 88 a and the second grooves 88 a and 88 bare preferably longitudinally-extending and generally hemi-spherical incross sectional shape. The resulting first and second interior cavities84 and 88 are longitudinally-extending and generally cylindricallyshaped and, as such, are adapted to totally enclose thecylindrically-shaped bodies of the first and second heating elements 86and 90, respectively, when the top 62 is secured to the bottom 60, asshown in FIG. 8.

The heating elements 86 and 90 can be any type suitable for providingthe required heat for sealing and suitable for fitting within theinterior cavities 84 and 88. The power rating and dimensions of thebodies of the heating elements 86 and 90 will vary depending on theparticular sealing operation and the particular structure of the crimper58. In one embodiment, the heating elements 86 and 90 operate at thirtysix volts and two hundred fifty watts, and have dimensions of 5/16 inchin diameter and 5⅝ inches in length.

The heating elements 86 and 90 have respective pairs of electrical wires96 and 98 that extend from the ends of the bodies thereof to anelectrical power circuit (not shown). The illustrated split crimper 58has a passageway 100 provided therein for the passage of the electricalwires 96 and 98 from the heating elements 86 and 90 to the exterior ofthe crimper 58. The passageway 100 can have any structure suitable forthis purpose. In the embodiment shown, the passageway 100 includes firstand second branch passages 102 and 104 that extend to the first andsecond interior cavities 84 and 88, respectively. The branch passages102 and 104 converge into a single passage 106 that extends to anopening 108 in the exterior of the crimper 58. In the preferredembodiment shown, the opening 108 is located in the base 60 of thecrimper 58, but alternatively it could be located in the top 62, orpartially in the top 62 and partially in the base 60. It should be notedthat the junctions between the electrical wires 96 and 98 and theheating elements 86 and 90 are totally enclosed and protected by thecrimper 58 when the top 62 is secured to the base 60.

When the split crimper 58 is assembled, the heating elements 86 and 90are positioned inside the interior cavities 84 and 88. Then, the top 62of the crimper 58 is positioned on the base 60. The split crimper 58preferably includes cooperating structures on the base 60 and the top 62to facilitate positioning them relative to one another. Any suitablestructures can be used for this purpose. In the embodiment shown, thebase 60 of the crimper 58 includes first and second keys 110 and 112that protrude from its inner surface 92. The keys 110 are locatedbetween the first and second grooves 84 a and 88 a in the base 60. Thetop 62 of the crimper 58 includes first and second slots 114 and 116 inits inner surface 94. The slots 114 and 116 are located between thefirst and second grooves 84 b and 88 b in the top 62. When the top 62 isplaced on the base 60, the keys 110 and 112 extend into the slots 114and 116 to position the top 62 relative to the base 60.

The base 60 and the top 62 of the split crimper 58 can be formed fromany suitable material. Preferably, they are formed from a strong, rigidmetal, such as steel. The base 60 and the top 62 can be manufactured inany suitable manner. For example, the base 60 and the top 62 can each bemanufactured by machining a blank of metal to include theabove-described structures. The blanks for manufacturing the base 60 andthe top 62 may be the same. Typically, once the crimping surface 70 isground on the top 62, the top 62 becomes dedicated to either an uppercrimper 52 or a lower crimper 56. For example, the top 62 may be a maleupper top or a female lower top, or a right hand upper top or a lefthand lower top. The base 60 is typically interchangeable between theupper crimper 52 and the lower crimper 56.

The top 62 of the split crimper 58 is removably attached to the base 60by any suitable retaining means. Preferably, the top 62 and the base 60each have at least four holes adapted for receiving fasteners forremovably attaching the top 62 to the base 60. In the preferredembodiment shown, the base 60 has four threaded holes 118 extending intothe four corners of its inner surface 92. The top 62 has four unthreadedholes 120, with enlarged upper ends 124 (see FIG. 9), extending throughits four corners. Four threaded fasteners 128 (two of which are shown inFIG. 9) are inserted into the aligned holes 118 and 120 until the headsof the fasteners 128 abut the bottom of the enlarged upper ends 124 ofthe holes 120. The use of four fasteners 128 in the four corners of thecrimper 58 creates a strong, stable attachment between the top 62 andthe base 60. It should be noted that the prior art crimper 10 shown inFIGS. 1 and 2 could not be modified to include both two heating elementsand four fasteners, because the ends of the heating elements wouldextend through the corners of the crimper and thereby block thelocations where the fasteners would be inserted.

Referring again to FIG. 3, in operation the upper and lower crimpers 52and 56 are respectively attached to the upper and lower crimper bars 50and 54 for rotation. Preferably, all of the upper and lower crimpers 52and 56 are split crimpers 58 according to the invention, as shown inFIGS. 6 through 10. As the folded sheet 30 of packaging material ismoved along the support surface 40 in the direction of the arrow, theupper crimpers 52 are rotated about the upper crimper bar 50 in acounterclockwise direction (as viewed from outside the drawing), and thelower crimpers 56 are rotated in a clockwise direction. As a result, theleading portions 74 of the crimping surfaces 70 (FIG. 8) of opposingupper and lower crimpers 52 and 56 initially engage the folded sheet 30of packaging material. When this occurs, the folded sheet 30 iscompressed between the downwardly facing crimping surface 70 of theupper crimper 52 and the upwardly facing crimping surface 70 of thelower crimper 56. As a result, the overlapping layers which make up thefolded sheet 30 of packaging material are sealed together to form atrailing edge seal for a packaged article 36 a.

One of the opposing upper and lower crimpers 52 and 56 can be equippedwith a blade, and the other can be equipped with an anvil. Furthermovement of the folded sheet 30 of packaging material, and furtherrotation of the upper and lower crimpers 52 and 56, brings the crimpers52 and 56 to a position where the blade is aligned with the anvil at alocation after the trailing edge seal of the packaged article 36 a.Consequently, the folded sheet 30 of packaging material is cutlongitudinally into two pieces at this location.

Still further movement of the folded sheet 30 of packaging material, andfurther rotation of the upper and lower crimpers 52 and 56, brings thecrimpers 52 and 56 to a position where the trailing portions 76 of thecrimping surfaces 70 (FIG. 8) engage the folded sheet 30. When thisoccurs, the folded sheet 30 is compressed between the downwardly facingcrimping surface 70 of the upper crimper 52 and the upwardly facingcrimping surface 70 of the lower crimper 56. As a result, theoverlapping layers which make up the folded sheet 30 of packagingmaterial are sealed together to form a leading edge seal for the nextpackaged article 36 a on the conveyor 38.

When either of the heating elements 86 or 90 requires replacement, thetop 62 of the split crimper 58 is initially removed from the base 60without disturbing the original set-up. This allows access to theheating element 86 or 90 for replacement. When the new heating element86 or 90 is installed, the top 62 is repositioned on the base 60 andattached with the fasteners 128. Advantageously, the base 60 remainsattached to the crimper bar 50 or 54 during the replacement of theheating element 86 or 90. As a result, it is unnecessary to perform atime consuming set-up operation on the split crimper 58 after replacingthe heating element 86 or 90.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been described in itspreferred embodiment. However, it should be noted that this inventionmay be practiced otherwise than as specifically illustrated anddescribed without departing from its scope. For example, the splitcrimper of this invention has been described and illustrated in thecontext of an otherwise conventional rotary crimping assembly. It willbe appreciated, however, that the split crimper of this invention may beutilized in other types of conventional crimping assemblies, such aswalking bar and intermittent crimping assemblies, wherein one or both ofthe crimpers are moved in such a manner as to engage and compress thepackaging material therebetween. The above-described rotary crimpingassembly includes upper and lower crimper bars that move the crimpersinto engagement with the overlapping layers of packaging material tocreate a seal. However, other types of crimping assemblies may includeother means for moving the crimpers into engagement with the layers ofpackaging material, in which case the split crimper would be adapted forattachment to that means. Although the opening 108 for passage of theelectrical wires 96 and 98 is located in the base 60 of the illustratedsplit crimper 58, alternatively the opening 108 could be located in thetop 62 of the split crimper 58. With such a design, the top 62 could bedesigned to be reversible on the base 60 so that the opening 108 ends upon a desired side of the crimping assembly regardless of which hand theassembly is.

1. A crimper for engaging and heat sealing overlapping layers of apackaging material comprising: a first crimper portion having a crimpingsurface; a second crimper portion secured to said first crimper portionto form a crimper, portions of said first and second crimper portionscooperating to define an interior cavity; and a heating element disposedcompletely within said interior cavity. 2-18. (canceled)